Table I.

Speed and Persistence Measurements for Wild-type and rasG⁻ Cells

		Wild-type (AX2)		rasG − (IR15)
Mean speed (μm/min)		4.5 ± 2.6		2.9 ± 2.4
Persistence		0.46		0.44

Cells were examined in a perfusion chamber as described in Materials and Methods. Images were recorded every minute, and the distance moved by the centroids of several cells was used to calculate the mean cell speed. The persistence, which represents the constancy of direction of each cell, was calculated as the cosine of the angle between consecutive paths.